When the plunge started at 9:30 a.m., the air temperature in Boston was 24 degrees and the water temperature in Boston Harbor was 42 degrees, according to the National Weather Service in Taunton.

“I sort of feel shocked that I did it,” said Maribeth Burke, 49, a West Roxbury resident who also took her first-ever plunge.

Over 600 people participated in the New Year’s Day rite held at the BCYF Curley Community Center in South Boston.

This year’s plunge was dedicated to the late William McDermott, a noted Boston election lawyer and loyal Brownie who was struck and killed by a car in February while crossing Day Boulevard at L Street.

“Billy was a wonderful friend to so many,” said Jack Dever, president of the L Street Brownies. “He was here with us every year, helping to organize all of this. We miss him.”

McDermott, who was 67, swam most days of the year in Dorchester Bay with his fellow Brownies. But on New Year’s Day, he never took the plunge, preferring to stay dry.

“He handed out the towels,” said his son, Liam McDermott, 35, who stood at the front of the pack, wearing a Boston College hockey jersey to honor his late father’s devotion to the Eagles.

McDermott and his sister, Deirdre Habershaw, 31, took the plunge in memory of their father.

“It’s 2014, and it will be a year of healing for us,” he said.

Money raised from the sale of t-shirts and hot chocolate will be donated to the South Boston Sports Hall of Fame Scholarship Fund and to the neighborhood’s youth hockey association.

Organizers hope to raise $3,000, enough to fund two scholarships for a high school graduate from South Boston.